We've been running this on the official TF2C Custom Maps server for a few weeks now, and have been able to playtest it a few times in a 12v12 non-competitive environment as a result.
The general user feedback regarding the overall layout so far has been fantastic. We've had people calling it more fun than Steel, specifically complimenting the wide variety of options for flanking. It's very open and it allows for all classes to find a unique way to play with the map.
Similar to Steel though, it tends to take people a while to learn, and the layout doesn't seem incredibly intuitive. This is a problem that's exaggerated by the ultra-casual setting in which it's being playtested, of course. But to give a few examples, Blue will often run into their courtyard that branches off into the other points during setup time, and then they'll struggle to find A after the round starts. Similarly, after capturing A, there is no clear path to B, so Blue starts to aimlessly wander afterwards. The dropdown behind A doesn't make it clear where it leads either, and since it closes after A is captured, I don't think I've ever seen anyone use it.
In general, a lot of newbie players will avoid playing any of the main points at all, and will solely attack/defend D. I think that, even if the map was totally plastered with signs over every single doorway indicating what point(s) it leads to, that would be an improvement for navigability (even if it'd look quite silly and redundant to those that already know the map). After C is captured, I've noticed that some people on Red will even wander off to A or some other unrelated point because they couldn't find the route to D.
There are also some design quirks that seem to confuse people. For whatever reason, the pit surrounding D isn't clear enough that it's a death pit, and I've seen players jump straight down into it assuming they'd live. Keeping with the aesthetic of the map, you could even put a water pit with some gators down there to make it more obvious that it'll kill the player.
There are also some windows overlooking D which are open and look like they can be fired through, but are ultimately solid. I've seen a soldier, more than once, blow himself up on this window by trying to fire through it.
Ultimately, the problems with the map are relatively minor and just come down to making the pathing and design more intuitive. But the gameplay is incredibly unique, balanced, and engaging. At its best, when playing with two balanced teams that are familiar with the quirks and layout of the map, it's a thrilling experience that constantly keeps me thinking of how I can surprise the enemy team to break their hold. It's a wonderful diamond in the rough, and seeing some of the rougher edges smoothed out would easily bring this up to a 5-star for me.